Intelligent Decoupling And Optimization Control Strategy And Its Application To Multiple Gas Collector Pressure In Coke-oven With Asymmetry

Coke is the main raw material in the metallurgical industry. In the coking process, large amount of by-product gas will be generated from coke-ovens, and the process of recycling by-product gas is called gas collecting process. It is an important link in the iron and steel production, which not only saves energy but also reduces environmental pollution. The stability of gas collector pressure directly influences the gas quality, the life-time of coke-ovens and the producing environment. Therefore, it is a vital significance for the iron and steel enterprise to study on the control of gas collecting process of multi asymmetrical coke ovens.The gas collecting process of multi asymmetrical coke ovens is a highly complex industrial process, which is multi-variable, strong coupling, asymmetry and nonlinearity, time-varying and hard in modeling, so it is difficult to acquire good control results with classical control theory or unique intelligent technology. An intelligent decoupling and optimization technology is proposed in this paper and a valid way is presented for the optimization problem in the gas collector pressure. The main achievement in this paper includes several aspects as follows:(1) Prediction model of gas collector pressure based on gray forecasting and BP neural networkAs the gas collecting process of multi asymmetrical coke ovens is a highly complex industrial process, which is difficult to obtain accurate mathematical model, an integrated modeling method which incorporated gray forecasting and BP neural network is proposed. Through analysis of the process mechanism and data of coke-ovens, the process of the gas collector pressure conditions has been divided into two, and the prediction modle of gas collector pressure based on gray forecasting and improved BP neural network is established, whichi can obtain accurate predictions of gas collector pressure.(2) Fuzzy doucoupling method based coupling analysis of gas collector pressure of coke-ovensThe gas collector pressure of a coke-oven with asymmetry has different capacity and its steel enterprises has different channels, which make the gas collecting process strong coupling, and based on this characteristics, a fuzzy decoupling control approach based on coupling analysis is developed. From the perspective of probability and statistics, the strong or weak coupling group for the asymmetrical gas collector pressure is real-time determined by coupling analysis method, which can reduce the inputs dimension of the follow-up control. And then strong or weak fuzzy decoupling controller is chosen for the corresponding gas collector pressure, which can realize decoupling of the gas collector pressure.(3) Intelligent control method of gas collector pressure of coke-ovensThe gas collector pressure of a coke-oven fluctuates sharply and changes suddenly, and based on this characteristic, a variable structure fuzzy control approach based on particle swarm optimization method is developed. In order to obtain a smooth switch, according to the established prediction model of gas collector pressure, fuzzy switching strategy is seclected. Two fuzzy controllers which use different control rules are designed according to different ranges of gas collector pressure. For the situation that fuzzy controller quantifiable factors are difficult to be modified, the adaptive tuning laws of PSO inertia coefficient are adopted to obtain the preferable fuzzy controller quantifiable factors. And butterfly valve controller is developed to adapt to the characteristics of butterfly valve so as to enhance the control quality. In coking plant production process, the target of gas collector pressure is difficult to adjust timely according to different conditions, the linear regression and RBF neural network are integrated to build dynamitic model for the gas collector pressure, which can obtain the different set point of the gas collector pressure according to different conditions, thus the cock-ovens can be ensure good run.(4) Intelligent decoupling and optimal control system and its applicationThe system frame is designed after the real-time, data collection and acquisition, reliability and safety are considered. The communication between the application soft and basic automation is realized with OPC and intelligent decoupling and optimization control technique for multiple gas collector pressure in coke-ovens with asymmetry is realized. The control algorithm has been applied in gas collecting processes of three coke ovens in an iron and steel enterprise. The actual running result shows that the control algorithm is simple, feasible, reliable, and easy to expand and has strong anti-disturbance ability. The control algorithm has realized the pressure stability of the gas collecting process of multi coke-ovens. In a word, it provides an efficient method for the decoupling and optimazation control of the gas collecting process of multi asymmetrical coke ovens.